Correct option is C
Total Cost Price = 2,000 × 10 + 1,000 = 20,000 + 1,000 = 21,000
The damaged boxes = 10 kg/20 kg per box = 0.5 box
Actual sold boxes = 10 boxes - 0.5 boxes = 9.5 boxes
Total Selling Price = 2,500 × 9.5 = 23,750
Gain = 23,750 - 21,000 = 2,750